Tonight has been absolutely huge for Playfish's Restaurant City, as the game has seen the release of new Halloween-themed recipes, and a traditional set of Halloween decorations, containing pumpkins, ghosts, and all of the decorations you would expect from a properly themed party. That isn't enough for this developer, however, as Playfish has added yet another feature to their Halloween extravaganza in the form of Halloween Mystery Boxes.

Meet us behind the break to find out how to get your hands on one of these boxes.

The Halloween Mystery Box feature is actually a bit more complicated than it might outwardly appear. There are three series of items to collect: Paranormal (vampires and werewolves), Witchy Wonder (witches and ghosts), and Trick or Treat (costumed royalty and pop culture references). Each series contains six different items to collect, and each Mystery Box you purchase contains a single item from one of the three series.

Once you complete one of the three series, you'll be rewarded with that particular series' completion bonus. For collecting all six of the Paranormal items, for instance, you'll earn the Paranormal Stove, which cooks food 30% faster than a traditional stove.

Taking things one step further, if you can collect each and every figurine (18 in all), you'll not only earn the three completion bonuses for finishing the three individual sets, but you'll receive the feature's ultimate prize: the Trick or Treat Monster House, an "arcade machine" item that generates 1,000 coins every four hours, and adds 3 points to your restaurant's maximum popularity rating.

Mystery Boxes can be purchased in three quantities - a single box costs 10 Playfish Cash, a bundle of six costs 50 Playfish Cash and a bundle of 13 boxes costs 100 Playfish Cash. This is one of the game's most expensive features to date, but luckily, Playfish says that you "shouldn't" receive duplicate items until you have completed your set, so at least that takes away some of the worry of potentially wasting real world money on duplicates.

To see images of the rest of the items up for grabs, check out the official Restaurant City Blog. Happy spooking!